WiredTree
Yes,
WiredTree is a good value.
2gb managed for $55 is quite decent. Five years ago ~$50 would barely get you 512mb!
(Note that WiredTree uses Virtuozzo, but that's probably not an issue if you're just running WordPress sites. Virtuozzo is not true isolation. It's not really "private", as it shares/pools CPU resources. It's 2000s technology. More modern 2010s VPS tech uses Xen, KVM, Hyper-V or VMware.)
And if you use them, use our link if you don't mind:
WiredTree.com
2gb RAM enough?
With only 20 (later 30-40) sites, I don't see any reason that 2gb will not work. The only mitigating factors are:
(1) traffic
(2) caching, or lack thereof
How many visitors do the sites (total) get monthly?
SSD
SSD is as overrated as LiteSpeed. More so, actually. Don't let that be a determining factor.
SSD mostly benefits databases, not static files.
For just WordPress sites, it honestly doesn't make a difference unless:
(1) the site traffic is very large -- ie, many MySQL read/writes
(2) it's poorly coded, and thus has lots of resource overhead -- especially MySQL
(3) you're not caching anything, and every call has to hit the databases
Sometimes just optimizing MySQL on the server is all you need. I often think these benchmarks that claim big % jumps are doing so with non-optimized servers.
A good RAID SAS disk array is just as good as an SSD in most situations, and far cheaper. Most all decent VPS hosts use RAIDed SAS HDD.
You don't need to avoid SSD, just don't think you *must* have it. What I always find silly is when Virtuozzo hosts offer it, but the CPU pooling of Vz is more often the server bottleneck and not the I/O.
If you do use SSD, just be sure to backup frequently, especially if the host is not running redundant failover clouds. SSD is far more volatile than HDD, and chances of recovery from an SSD is near zero. (We're about to use Idera CDP5 backups from x10's r1softlicenses.com for daily backups. For a small VPS, it's only $15 monthly.)
In practice, you might get a 10% performance boost from SSD. So a site with page loads of 2s would maybe be 1.8s. Not a big difference.
LiteSpeed
Aside from LiteSpeed itself, I've never seen clear evidence that the webserver is all that.
Yes, it's ideal as an Apache drop-in for shared hosts. It's easy. But for users like us, it's vastly overpriced. Whatever bugs nginx or Varnish introduces (rare!) to our sites can easily be sorted, especially if using a cPanel plugin. LiteSpeed is mostly for shared hosting customers, not VPS/dedicated users.
LiteSpeed also has many drawbacks, one of which is the mod_security compatibility issue.